Amigrenin

Amigrenin film-coated tablets are indicated for the acute relief of migraine attacks, with or without aura. Amigrenin film-coated tablets should only be used where there is a clear diagnosis of migraine.

Posology

Adults

Amigrenin film-coated tablets are indicated for the acute intermittent treatment of migraine. They should not be used prophylactically.

It is advisable that Amigrenin film-coated tablets be given as early as possible after the onset of migraine attack but it is equally effective at whatever stage of the attack it is administered.

The recommended dose of oral Amigrenin film-coated tablets is a single 50 mg tablet. Some patients may require 100 mg. If the patient has responded to the first dose but the symptoms recur a second dose may be given in the next 24 hours provided that there is a minimum interval of two hours between the two doses. No more than 300 mg should be taken in any 24 hour period.

Patients who do not respond to the prescribed dose of Amigrenin film-coated tablets should not take a second dose for the same attack. In these cases the attack can be treated with paracetamol, acetylsalicylic acid, or non-steroidal anti-inflammatory drugs. Amigrenin film-coated tablets may be taken for subsequent attacks.

Amigrenin film-coated tablets is recommended as monotherapy for the acute treatment of migraine and should not be given concomitantly with ergotamine or derivatives of ergotamine (including methysergide).

Paediatric population

The efficacy and safety of Amigrenin film-coated tablets in children aged less than 10 years have not been established. No clinical data are available in this age group.

The efficacy and safety of Amigrenin film-coated tablets in children 10 to 17 years of age have not been demonstrated in the clinical trials performed in this age group. Therefore the use of Amigrenin film-coated tablets in children 10 to 17 years of age is not recommended.

Elderly (Over 65 years of age)

Experience of the use of Amigrenin film-coated tablets in patients aged over 65 years is limited. The pharmacokinetics do not differ significantly from a younger population but until further clinical data are available, the use of Amigrenin film-coated tablets in patients aged over 65 years is not recommended.

Method of administration

The tablets should be swallowed whole with water.

Amigrenin should not be given to patients who have had myocardial infarction or have ischaemic heart disease, coronary vasospasm (Prinzmetal's angina), peripheral vascular disease or patients who have symptoms or signs consistent with ischaemic heart disease.

Amigrenin should not be administered to patients with a history of cerebrovascular accident (CVA) or transient ischaemic attack (TIA).

Amigrenin should not be administered to patients with severe hepatic impairment.

The use of Amigrenin in patients with moderate and severe hypertension and mild uncontrolled hypertension is contraindicated.

The concomitant administration of ergotamine or derivatives of ergotamine (including methysergide) or any triptan/5-hydroxytryptamine₁ (5-HT₁) receptor agonist with Amigrenin is contraindicated.

Concurrent administration of monoamine oxidase inhibitors and Amigrenin is contraindicated.

Amigrenin film-coated tablets must not be used within two weeks of discontinuation of therapy with monoamine oxidase inhibitors.

Amigrenin film-coated tablets should only be used where there is a clear diagnosis of migraine.

Amigrenin is not indicated for use in the management of hemiplegic, basilar or ophthalmoplegic migraine.

The recommended doses of Amigrenin should not be exceeded. As with other migraine therapies, before treating headaches in patients not previously diagnosed as migraineurs, and in migraineurs who present atypical symptoms, care should be taken to exclude other potentially serious neurological conditions.

It should be noted that migraineurs may be at risk of certain cerebrovascular events (e.g. cerebrovascular accident, transient ischaemic attack).

Following administration, Amigrenin can be associated with transient symptoms including chest pain and tightness which may be intense and involve the throat. Where such symptoms are thought to indicate ischaemic heart disease, no further doses of Amigrenin should be given and appropriate evaluation should be carried out.

Amigrenin should not be given to patients with risk factors for ischaemic heart disease, including those patients who are heavy smokers or users of nicotine substitution therapies, without prior cardiovascular evaluation. Special consideration should be given to postmenopausal women and males over 40 with these risk factors. These evaluations however, may not identify every patient who has cardiac disease and, in very rare cases, serious cardiac events have occurred in patients without underlying cardiovascular disease.

Amigrenin should be administered with caution to patients with mild controlled hypertension, since transient increases in blood pressure and peripheral vascular resistance have been observed in a small proportion of patients.

There have been rare post-marketing reports describing patients with serotonin syndrome (including altered mental status, autonomic instability and neuromuscular abnormalities) following the use of a selective serotonin reuptake inhibitor (SSRI) and Amigrenin. Serotonin syndrome has been reported following concomitant treatment with triptans and serotonin noradrenaline reuptake inhibitors (SNRIs).

If concomitant treatment with Amigrenin and an SSRI/SNRI is clinically warranted, appropriate observation of the patient is advised.

Amigrenin should be administered with caution to patients with conditions which may affect significantly the absorption, metabolism or excretion of drugs, e.g. impaired hepatic or renal function. A 50mg dose should be considered in patients with hepatic impairment.

Amigrenin should be used with caution in patients with a history of seizures or other risk factors which lower the seizure threshold, as seizures have been reported in association with Amigrenin.

Patients with known hypersensitivity to sulphonamides may exhibit an allergic reaction following administration of Amigrenin. Reactions may range from cutaneous hypersensitivity to anaphylaxis. Evidence of cross-sensitivity is limited, however, caution should be exercised before using Amigrenin in these patients

Undesirable effects may be more common during concomitant use of triptans and herbal preparations containing St John's Wort (Hypericum perforatum).

Prolonged use of any type of painkiller for headaches can make them worse. If this situation is experienced or suspected, medical advice should be obtained and treatment should be discontinued. The diagnosis of medication overuse headache (MOH) should be suspected in patients who have frequent or daily headaches despite (or because of) the regular use of headache medications.

Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine as it contains lactose.

No studies on the effects on the ability to drive and use machines have been performed. Drowsiness may occur as a result of migraine or its treatment with Amigrenin. This may influence the ability to drive and to operate machinery.

Adverse events are listed below by system organ class and frequency. Frequencies are defined as:

very common (>1/10), common (>1/100, <1/10), uncommon (>1/1,000, <1/100), rare (>1/10,000, <1/1,000), very rare (<1/10,000), not known (cannot be estimated from the available data). Some of the symptoms reported as undesirable effects may be associated symptoms of migraine.

Clinical Trial Data

Post-Marketing Data

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.

Doses in excess of 400 mg orally were not associated with side effects other than those mentioned.

If overdosage occurs, the patient should be monitored for at least 10 hours and standard supportive treatment applied as required.

It is unknown what effect hemodialysis or peritoneal dialysis has on the plasma concentrations of Amigrenin.

Pharmacotherapeutic group: Analgesics: Selective 5-HT₁ receptor agonists.

ATC code: N02CC01

Mechanism of action

Amigrenin has been demonstrated to be a specific and selective 5-Hydroxytryptamine₁ (5HT_1D) receptor agonist with no effect on other 5HT receptor (5-HT₂-5-HT₇) subtypes. The vascular 5-HT_1D receptor is found predominantly in cranial blood vessels and mediates vasoconstriction. In animals, Amigrenin selectively constricts the carotid arterial circulation but does not alter cerebral blood flow. The carotid arterial circulation supplies blood to the extracranial and intracranial tissues such as the meninges and dilatation of and/or oedema formation in these vessels is thought to be the underlying mechanism of migraine in man.

In addition, evidence from animal studies suggests that Amigrenin inhibits trigeminal nerve activity. Both these actions (cranial vasoconstriction and inhibition of trigeminal nerve activity) may contribute to the anti-migraine action of Amigrenin in humans.

Clinical efficacy and safety

Amigrenin remains effective in treating menstrual migraine i.e. migraine without aura that occurs between 3 days prior and up to 5 days post onset of menstruation. Amigrenin should be taken as soon as possible in an attack.

Clinical response begins around 30 minutes following a 100mg oral dose.

Although the recommended dose of oral Amigrenin is 50mg, migraine attacks vary in severity both within and between patients. Doses of 25 - 100mg have shown greater efficacy than placebo in clinical trials, but 25mg is statistically significantly less effective than 50 and l00mg.

A number of placebo-controlled clinical studies assessed the safety and efficacy of oral Amigrenin in approximately 800 children and adolescent migraineurs aged 10 to 17 years. These studies failed to demonstrate relevant differences in headache relief at 2 hours between placebo and any Amigrenin dose. The undesirable effects profile of oral Amigrenin in adolescents aged 10-17 years was similar to that reported from studies in the adult population.

Following oral administration, Amigrenin is rapidly absorbed, 70% of maximum concentration occurring at 45 minutes. After 100mg dose, the maximum plasma concentration is 54ng/ml. Mean absolute oral bioavailability is 14% partly due to presystemic metabolism and partly due to incomplete absorption. The elimination phase half-life is approximately 2 hours, although there is an indication of a longer terminal phase. Plasma protein binding is low (14-21%), mean volume of distribution is 170 litres. Mean total plasma clearance is approximately 1160ml/min and the mean renal plasma clearance is approximately 260ml/min. Non-renal clearance accounts for about 80 % of the total clearance. Amigrenin is eliminated primarily by oxidative metabolism mediated by monoamine oxidase A. The major metabolite, the indole acetic acid analogue of Amigrenin is mainly excreted in the urine, where it is present as a free acid and the glucuronide conjugate. It has no known 5HT1 or 5HT2 activity. Minor metabolites have not been identified. The pharmacokinetics of oral Amigrenin do not appear to be significantly affected by migraine attacks.

In a pilot study, no significant differences were found in the pharmacokinetic parameters between the elderly and young healthy volunteers.

Amigrenin was devoid of genotoxic and carcinogenic activity in in-vitro systems and animal studies.

In a rat fertility study oral doses of Amigrenin resulting in plasma levels approximately 200 times those seen in man after a 100 mg oral dose were associated with a reduction in the success of insemination.

This effect did not occur during a subcutaneous study where maximum plasma levels achieved approximately 150 times those in man by the oral route.

In rabbits embryolethality, without marked teratogenic defects, was seen. The relevance for humans of these findings is unknown.

Not applicable.

No special requirements